1. Helsinki University of Technology, Laboratory of Industrial Chemistry, P.O. Box 6100, FIN-02015 HUT, Finland, Fortum Oil and Gas Scientific Services, P.O. Box 310, FIN-06101 Porvoo, Finland, Institute of Chemical Physics and Biophysics, Akadeemia 23, 12618 Tallinn, Estonia, Calipso b.v., P.O. Box 513, 5600 MB Eindhoven, The Netherlands, and Fortum Oil and Gas Oy, P.O. Box 110, FIN-00048 Fortum, Finland